Fluorescent Composition
Compositions in which a particle (such as a hydrophobic silica aerogel) is coated with a fluorescent material are known. As an example of this type of prior art, U.S. Pat. No. 2,935,481 to Hochwalt discloses use of a hydrophobic silica as a carrier for a water-soluble fluorescent dye that may be present as a mere surface coating or as an absorbed or adsorbed coating. The fluorescent dye of Hochwalt is releasably coated onto the silica, whereby the dye is released when the coated silica is placed in an aqueous solution.
It was also known to the prior art to use an organic scintillator in a radiation-sensitive layer in a radiation-sensitive recording element, as exemplified by the disclosure in U.S. Pat. No. 3,513,102 to Heidke. In this type of prior art, the organic scintillator is dissolved along with a solid-solution carrier (such as a water-insoluble resin) in a solvent, and the resulting solution is dispersed in an aqueous solution of a hydrophilic colloid prior to coating the dispersion onto a substrate so as to form a radiation-sensitive layer.
It was also known to the prior art to produce a plastic phosphor bead having a cross-linked polymer matrix (such as polyvinyltoluene cross-linked with divinylbenzene), with the fluorescent material being dissolved in solid solution within the bead. Illustrative of this type of prior art is U.S. Pat. No. 3,150,101 to Heimbuch.
Highly fluorescent organic compounds (i.e., highly fluorescent materials) are well known in the art, as exemplified by U.S. Pat. Nos. 3,666,683 and 3,314,894 and by the patents to Heidke and Heimbuch discussed above. U.S. Pat. No. 3,930,063 to Miller et al. discloses mixing together a silica salt having large particle size and a fluorescent dye.
It was known to the prior art to affix an alkyl or aryl substituent to the surface of siliceous materials by covalent chemical bonding with the resultant bonded materials being used for chromatography. Exemplary of this type of prior art is Locke et al., Analytical Chemistry, Vol. 44, No. 1, pages 90-92 (January 1972). It was also known to react a siliceous surface with monohalogenated silanes, silazanes or silylamines, or with monoalkoxy or monoacetoxysilanes, and then to cause a chemical modification of the reaction product. Such reaction products are useful for high-resolution chromatography. This type of prior art is illustrated by U.S. Pat. No. 4,043,905 to Novotny et al.
The prior art discussed above is pertinent with respect to the fluorescent composition of the present invention. However, none of this prior art discloses a composition comprising an inert porous particle to which a highly fluorescent material is fixedly attached by covalent chemical bonding.